Research On Electromagnetic Disturbance Of Intelligent Components Caused By Substation Ground Potential Rise

Intelligent components have faced even worse electromagnetic environment in substations because of on-site installation,and the level of electromagnetic compatibility of intelligent components has become a major factor that restricts the safe and stable operation of intelligent components.In the electromagnetic disturbance of the intelligent components,the probability of the electromagnetic disturbance of the intelligent components caused by the ground potential of substations grounding network is large,and the interference effect is serious.Therefore,in this paper focuses on ground potential distribution characteristics under the short-circuit and pulse current and its electromagnetic interference to the intelligent components,research on the affect the law of electromagnetic disturbance of intelligent components caused by substation ground potential rise through modeling calculation and actual measurement.Firstly,a simulation model of grounding grid is established by using CDEGS,and the distribution of ground potential rise of grounding grid under the fault of power frequency short-circuit is calculated.However,there is a big gap of the current spreading characteristics of grounding grid under power frequency current or pulse current.Based on the soil discharge characteristics,frequency-changing characteristics and the inductive reactance effect of grounding grid under the pulse current,a staged equivalent model of grounding grid is established.The iterative algorithm based on Fourier transform and moment method is used to simulate and analyze the influence of waveform,amplitude,injection location and grounding grid arrangement on the potential distribution and impedance.Then,based on the calculation characteristics of ground potential rise and disturbance of intelligent components,a harassment coupling model of grounding network and shielded cable is established.According to the operating parameters of a 220 k V substation,the transient current into the ground through lightning arrester wave was calculated by EMTP simulation.According to the calculation method of shielding cable disturbance voltage,the ground potential caused by the short-circuit of ground fault,direct lightning and arrester action and the harassment voltage of the intelligent components was calculated,and the influence of the current injection position,the number of shunt lines,the shielded cable grounding mode and the secondary equipotential ground network on the electromagnetic disturbance of intelligent components was obtained.Finally,in order to verify the correctness of the simulation results and realize the long-term monitoring of substation ground potential rise,aiming at the specific characteristics of substation electromagnetic environment and the amplitude and broadband of ground potentials caused by the pulse current,a set of ground potential rise test system suitable for substation site application has been developed.And through the field simulation test,the ground potential of the grounding grid and the port harassment voltage of the shielded cable are obtained under the surge voltage.The correctness of the simulation model and the calculation method are verified by comparison with the experimental results.It provides the basis for the electromagnetic disturbance prediction and monitoring of intelligent components in substation and the design of anti-ground potential rise interference.